So I'm fairly comfortable around a bike but this is an issue I haven't encountered before. I have a new bike (Jamis Renegade Expat). The bike has a compact double chainring.

On the last 2 rides I have had the following issue. It doesn't happen every. I will shift to the small chainring without issue. When I then attempt to shift back into the large chainring, it lever moves as if it isn't even connected to the cable. It has no resistance and the front shifter doesn't move.

Today after about 15 miles I randomly tried the lever and it shifted into the large ring without issue.

Like I said I have had this numerous times, although not every time I shift down and back. And it does seem to work again eventually.

Since the bike is new I am planning on taking it back to the dealer, but before I did I was figuring I would ask in case it is maybe something silly I can just fix and not waste the time taking it back for repair.

IDK, I'd have to be there. maybe it's user technique shifting under a load, etc. , stuff I cannot Guess..

some one from the shop may ride along with you to see your situation replicated..





./.

It's not a technique issue. The shifter will move free even when the bike is stationary, which usually you can't since it is actually trying to move the shifter which won't work if you aren't pedaling.

I put the bike on the stand and made a quick video to illustrate. you can hear the shifter make a small click, which almost seems like it is trying to grab the cable and doesn't. But the shifter moves freely because it isn't pulling on the cable at all.

It's looks like there isn't enough tension in the cable.

Does the trim work ?

Have you tried setting up the front derailleur from scratch ?

You can check if there is a fault of the shifter if you unhook the cable and hold it between your fingers and operate the shifter with the other hand. Does the cable move as it should when you shift through the clicks ?


Follow this set up guide for the 4700 FD - on page 2
https://www.bikeforums.net/bicycle-me...rubbing-2.html

It is the fault of the shifter. when I am moving the lever in the video the cable is not moving. It still has appropriate tension. And as I mentioned it will work out of the blue. After I stopped the video it actually moved the lever and it grabbed the cable and I was able to spin the pedals and shift. Then I shifted down into the small ring again and it wouldn't shift again. If I had a way to hold the camera and do all of that at the same time I would have.

What I am unsure of is if there is anything user serviceable within the shifter or just take it to the shop. It's only 6 months old so it should still be under warranty. I mostly don't want to have to run it down, drop it off, be without the bike until its fixed etc. That's largely why I got into doing my own bike maintenance decades ago.

since its a new bike take it back to the shop and show them it could be a warranty issue at the very least they will fix it, my old ultegra shifter(10 speed) is a little inconsistent in a similar way when I get around to it I plan to flush it out with wd40 and reset the cable tension which has yet to fail me on all manner of shifters.

OK you are a Video maker not a Mechanic .. I get that part.

Wow, nice and helpful thanks. No I haven't ever worked at a bike shop. But I have built, rebuilt, repaired, and tuned all of my bikes. But in the 25 or so years I have been I've never had a brifter act like this so I thought I'd ask.

So i take it you have done all of the above and have already removed the cable from the shifter and eliminated every other possible causes like a damaged cable, unseated cable end, or kink in the cable causing too much friction ?

The shifter can be re-lubed but no serviceable parts are available.

If you are certain it's a fault. The only option is a warranty return and replacement.

^ that is a reasonable Check List ^.. of things that you could have done , Did You? IDK..

Did I completely tear it down? No. If the bike was 5 years old with thousands of miles I would have, and probably just troubleshot all the way to the end on my own. But I'm not gonna tear down a 6 month old bike that is still under warranty if I don't have to. At the same time if it was something that someone else had seen before that was like "oh yea I've seen that and you can just fix it quickly like so..." I would, vs driving an hour to take it back to the shop I bought it from.

So I posted here mostly to see if anyone else had seen a similar issue with an obvious yea sounds broken or yea its likely X to fix. I guess I was thinking along the lines of my day job in IT, where even my employees will bounce things off of me like "have you seen this issue before" because after having done it for 30 years the answer is usually "yea I have".


The first reply was largely "I'd have to see it to really have any idea". So I made a quick video to try and demonstrate it. That was obviously not illustrative enough to make a determination. So I'll just drop it off. No point risking shooting myself in the foot with the warranty.

Thanks for the looking and trying to help. I do appreciate it.

This really seems like a bad shifter issue to me. Older shifters with many miles and dried out grease can have the little shifting pawls stick and not engage properly with the mechanism in order to pull the cable. This is remedied by WD40 flushing and then re-lubing as best you can. My last bike needed this after probably 20k miles of use on the 2005 ultegra shifters. New shifters should never exhibit that behavior, so taking it in is exactly what you should do, and DO NOT let them WD40 flush it. If it's doing this after only 6mo. moderate use, something is fishy. My guess is an issue with the pawl or pawl spring. And since these are not serviceable, my guess is that they should give you a new shifter.

If the cable was frayed and catching or broken, it would not occasionally shift perfectly, you are correct about this.

-Jeremy

Thanks again for everyone who responded. Just as a follow up it was broken. Getting replaced under warranty from Shimano.